Gravel Packing Fluids and Methods Related Thereto

ABSTRACT

Gravel packing particles like sand are commonly used in sand control operations to form gravel packs for controlling the migration of formation particulates into a wellbore and wellbore production equipment. Gravel packing fluids and methods of sand control operations may also use petroleum coke gravel packing particles composed of fluid coke and/or flexicoke material. Such petroleum coke gravel packing particles may have improved transport into wellbores because of their lower density compared to traditional gravel packing material and may produce fewer fines that can plug gravel packs.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 63/265,050, entitled “Gravel Packing Fluids and Methods Related Thereto,” filed Dec. 7, 2021, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

This application relates to sand control operations, and, in particular, to gravel packing material formed from petroleum coke, and methods related thereto.

BACKGROUND OF THE INVENTION

In the oil and gas industry, hydrocarbons can be produced from subterranean formations penetrated by a wellbore. Efficient control of the movement of unconsolidated formation particulates into the wellbore, such as sand or other debris, has long been a pressing concern. These unconsolidated formation particulates may be produced during completion and production operations, due to formation movement related thereto or other causes (e.g., wellbore collapse). The creation of such unconsolidated formation particulates may be exacerbated in wellbores, whether vertical, horizontal, or otherwise deviated using hydraulic fracturing. Formation particulates may adversely affect the productivity of the wellbore, being drawn into wellbore production equipment and causing numerous problems, such as plugging production tubing and subsurface flowlines and the eventual erosion of flowlines, valves, downhole pumps, and fluid separation equipment at the surface, potentially necessitating costly remediation activities or abandonment of the wellbore altogether.

To control the migration of formation particulates into a wellbore and wellbore production equipment, sand control screen assemblies are often installed downhole across formations. A typical sand control screen assembly includes a screen made of wire or metal wrapped about a perforated base pipe. Sand control screen assemblies allow fluids to flow therethrough and into a wellbore base pipe but prevent the influx of particulate matter of a predetermined size and greater. The effectiveness of a sand control screen assembly can be augmented, horizontal wellbores, by installing a gravel pack in the wellbore annulus between the sand control screen assembly and the wellbore.

SUMMARY OF INVENTION

This application relates to sand control operations, and, in particular, to gravel packing material formed from petroleum coke, and methods related thereto.

In nonlimiting aspects of the present disclosure, a gravel packing fluid is provided including a carrier fluid; and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having an apparent density of less than about 1.7 g/cc.

In nonlimiting aspects of the present disclosure, a method is provided of introducing a gravel packing fluid into a subterranean formation, the gravel packing fluid comprising a carrier fluid and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having a density of less than about 1.7 g/cc.

These and other features and attributes of the disclosed petroleum coke gravel packing material of the present disclosure and their advantageous applications and/or uses will be apparent from the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:

FIG. 1 illustrates a scanning electron microscope image providing a representative embodiment of the shape of 40/70 mesh petroleum fluid coke gravel packing particles according to one or more aspects of the present disclosure.

FIG. 2A illustrates a particle size distribution chart of samples of fluid coke gravel packing particles for use in one or more aspects of the present disclosure.

FIG. 2B illustrates a particle size distribution chart of samples of flexicoke gravel packing particles for use in one or more aspects of the present disclosure.

FIG. 3 illustrates a chart of the results of permeability testing of samples of fluid coke and flexicoke gravel packing particles for use in one or more aspects of the present disclosure.

FIG. 4A illustrates a chart of the results of conductivity testing of samples of fluid coke and flexicoke gravel packing particles for use in one or more aspects of the present disclosure.

FIG. 4B illustrates a sieve size chart of the size of the tested fluid coke and flexicoke gravel packing particle samples of FIG. 4A both before and after conducting the conductivity testing.

DETAILED DESCRIPTION OF THE INVENTION

This application relates to sand control operations, and, in particular, to gravel packing material formed from petroleum coke, and methods related thereto.

As discussed above, control of the migration of formation fines may be facilitated by the use of a sand screen control assembly and installation of a gravel pack within the annulus between the wellbore and the sand control screen assembly (collectively, a “sand control operation”). However, oftentimes there are difficulties encountered during gravel packing operations. Gravel packing materials are delivered to a wellbore in a carrier fluid and maintained in suspension through the use of fluid viscosity, as well as turbulence controlled by fluid flow (pump) rate. Adequate suspension and transport of the gravel packing materials in a carrier fluid is needed to permit formation of an efficient gravel pack capable of sand control and fluid permeability and conductivity. Moreover, fine-grained particles (referred to as “fines”) produced from crushing of a gravel packing material, such as due to the force of produce fluids or formation movement, can plug the gravel pack and lessen its permeability and conductivity, thereby negatively impacting the wellbore's productivity.

Traditional gravel packing materials include relatively high density sand (˜2.5-2.7 grams per cubic centimeter (g/cc)), bauxite (˜3.5-3.8 g/cc), and ceramic (˜2.0-3.0 g/cc), and some issues may be associated with their use. First, these high density gravel packing materials often result in transport difficulties, requiring particularly high density and/or high viscosity carrier fluids (i.e., high polymer viscosifier loading) and thus necessitating relatively low fluid flow (pump) rates, which can lead to wellbore screen-out or other complications. Second, some traditional gravel packing materials are prone to fines production due to low crush strength values, thus reducing permeability and conductivity of the gravel pack.

The present disclosure alleviates the foregoing difficulties and provides related advantages as well. In particular, the present disclosure provides a low density gravel packing material composed of petroleum coke, and, particularly, fluid coke and/or flexicoke. The low density petroleum coke gravel packing materials described herein can be effectively suspended in a low viscosity carrier fluid and delivered at a high flow rate into a wellbore for sand (unconsolidated particulates) control and exhibit high crush strengths, thereby addressing two shortcomings of traditional gravel packing materials. It is to be understood that the term “petroleum coke,” as used herein, refers to both fluid coke and flexicoke, unless otherwise stated for ease of description. Accordingly, the “petroleum coke” of the present disclosure is distinguished from delayed coke and other types of coke that have very different properties and are not considered suitable for use as a gravel packing material, as described hereinbelow.

By using fluid coke and/or flexicoke as gravel packing material, CO₂ emissions are reduced as the coke could otherwise be used as a fuel source. In effect, using the petroleum coke gravel packing material described herein is a form of sequestering carbon that would otherwise contribute to CO₂ emissions.

Moreover, as described in greater detail hereinbelow, the petroleum coke gravel packing material for use in sand control operations of the present disclosure can additionally allow for extended gravel pack lengths, prevent issues often associated with gravel packs (e.g., fines formation and migration, shale spalling, and the like), permit a gravel packing operation to be ceased at any time without affecting the suspension (buoyancy) of the petroleum coke gravel packing material, and reduce costs of the gravel packing operation (e.g., lower pump rates, reduced viscosifier loadings, reduced gravel packing material costs, and the like).

Fluid coking is a carbon rejection process that is used for upgrading heavy hydrocarbon feeds and/or feeds that are challenging to process. The process produces a variety of lighter, more valuable liquid hydrocarbon products, as well as a substantial amount of fluid coke as byproduct. The fluid coke byproduct comprises high carbon content and various impurities. The fluid coking process may be manipulated to obtain fluid coke having the distinctive characteristics described herein that are suitable for use as gravel packing material, including as a supplement or replacement to traditional gravel packing material.

Flexicoke is produced from a modified variation of fluid coking, termed FLEXICOKING™ (trademark of ExxonMobil Research and Engineering Company (“ExxonMobil”)). FLEXICOKING™ is based on fluidized bed technology developed by ExxonMobil, and is a carbon rejection process that is used for upgrading heavy hydrocarbon feeds (referred to as “residua”). Unlike fluid coking, which utilizes a reactor and a burner, the FLEXICOKING™ process uses a reactor, a heater, and a gasifier. The FLEXICOKING™ process is described in greater detail below.

Illustrative petroleum coke (including either or both of fluid coke or flexicoke) gravel packing particles of the present disclosure may have, among other characteristics, an apparent density of less than 1.7 g/cc, and are suitable for inclusion in a carrier fluid for gravel packing during a sand control completion operation within a horizontal, vertical, or tortuous wellbore, including hydrocarbon-bearing production wellbores and water-bearing production wellbores.

Definitions and Test Methods

As used herein, the term “sand control operation,” and grammatical variants thereof, refers to a wellbore comprising a screen surrounding a drilled wellbore, either an open hole or cased hole wellbore, in a subterranean formation and an annulus formed between the screen and the wellbore, the annulus being packed with gravel packing material. As used herein, the term “gravel pack,” and grammatical variants thereof, refers to a collection of gravel packing particles. The gravel pack is designed to prevent production of unconsolidated formation particulates (e.g., sand) while maintaining permeability and conductivity for production of wellbore fluids.

As used herein, the term “carrier fluid,” and grammatical variants thereof, refers to a fluid used to transport gravel packing material into a wellbore, which may include various additives, without departing from the scope of the present disclosure, and as would be apparent by one of ordinary skill in the art in light of the present disclosure.

As used herein, the term “petroleum coke,” and grammatical variants thereof, refers to fluid coke or flexicoke, and is used herein to represent both unless otherwise indicated. The petroleum coke described herein is used as a low density gravel packing material for forming a gravel pack during a sand control operation. The term “petroleum coke gravel packing material” refers to gravel packing material composed of fluid coke or flexicoke, and is used interchangeably with the term “petroleum coke gravel packing particles.”

As used herein, the term “fluid coke,” and grammatical variants thereof, refers to the solid concentrated carbon material remaining from fluid coking. The term “fluid coking” refers to a thermal cracking process utilizing fluidized solids for the conversion of heavy, low-grade hydrocarbon feeds into lighter products (e.g., upgraded hydrocarbons), producing fluid coke as a byproduct. The term “fluid coke gravel packing material” refers to gravel packing material composed of fluid coke, and is used interchangeably with the term “fluid coke gravel packing particles.”

The fluid coke gravel packing material described herein may have a carbon content of 75 weight percent (wt %) to 93 wt %, or 78 wt % to 90 wt %; a weight ratio of carbon to hydrogen of 30:1 to 50:1, or 35:1 to 45:1; an impurities content (weight percent of all components other than carbon and hydrogen) of 5 wt % to 25 wt %, or 10 wt % to 20 wt %; a sulfur content of 3 wt % to 10 wt %, or 4 wt % to 7 wt %; and a nitrogen content of 0.5 wt % to 3 wt %, or 1 wt % to 2 wt %, each encompassing any value and subset therebetween.

As used herein, the term “flexicoke” refers to the solid concentrated carbon material produced from FLEXICOKING™. The term “FLEXICOKING™” refers to a thermal cracking process utilizing fluidized solids and gasification for the conversion of heavy, low-grade hydrocarbon feeds into lighter hydrocarbon products (e.g., upgraded, more valuable hydrocarbons). The term “flexicoke gravel packing material” refers to gravel packing material composed of flexicoke partially gasified fluid coke), and is used interchangeably with the term “flexicoke gravel packing particles.”

Briefly, the FLEXICOKING™ process in which the flexicoke for forming the flexicoke gravel packing material described herein, integrates a cracking reactor, a heater, and a gasifier into a common fluidized-solids (coke) circulating system. A feed stream (of residua) is fed into a fluidized bed, along with a stream of hot recirculating material to the reactor. From the reactor, a stream containing coke is circulated to the heater vessel, where it is heated. The hot coke stream is sent from the heater to the gasifier, where it reacts with air and steam. The gasifier product gas, referred to as coke gas, containing entrained coke particles, is returned to the heater and cooled by cold coke from the reactor to provide a portion of the reactor heat requirement, which is typically about 496° C. to about 538° C. A return stream of coke sent from the gasifier to the heater provides the remainder of the heat requirement. The coke meeting the heat requirement is then circulated to the reactor and the feed stream is thermally cracked to produce light hydrocarbon liquids that are removed from the reactor and recovered using conventional fractionating equipment. Fluid coke is formed from the thermal cracking process and settles (deposits) onto the “seed” fluidized bed coke already present in the reactor—the resultant at least partially gasified coke is flexicoke. In some instances, the coke from the thermal cracking process deposits in a pattern that appears ring-like atop the surface of the seed coke. Flexicoke is continuously withdrawn from the system during normal FLEXICOKING™ processing (e.g., from the reactor or after it is streamed to the heater via an elutriator) to ensure that the system maintains particles of coke in a fluidizable particle size range. Accordingly, flexicoke is a readily available byproduct of the FLEXICOKING™ process.

The flexicoke gravel packing material described herein may have a carbon content of 85 wt % to 99 wt %, or 90 wt % to 96 wt %; a weight ratio of carbon to hydrogen of 80:1 to 98:1, or 85:1 to 95:1; an impurities content (weight percent of all components other than carbon and hydrogen) of 1 wt % to 15 wt %, or 3 wt % to 10 wt %; a combined vanadium and nickel content of 3000 ppm to 45,000 ppm, or 3000 ppm to 15,000 ppm, or 5000 ppm to 30,000 ppm, or 30,000 ppm to 45,000 ppm; a sulfur content of 0 wt % to 5 wt %, or 0.5 wt % to 4 wt %; and a nitrogen content of 0 wt % to 3 wt %, or 0.1 wt % to 2 wt %, each encompassing any value and subset therebetween.

As used herein, the term “apparent density,” and grammatical variants thereof, with reference to the density of gravel packing particles, refers to the density of the individual particles themselves, which may be expressed in grams per cubic centimeter (g/cc). The apparent density values of the present disclosure are based on the American Petroleum Institute's Recommended Practice 19C (hereinafter “API RP-19C”) standard entitled “Measurement of Properties of Proppants Used in Hydraulic Fracturing and Gravel-packing Operations” (Second Ed., September 2020).

As used herein, the terms D10, D50, and D90 are used to describe particle sizes. As used herein, the term “D10” refers to a diameter at which 10% of the sample (on a volume basis unless otherwise specified) is comprised of particles having a diameter less than said diameter value. As used herein, the term “D50” refers to a diameter at which 50% of the sample (on a volume basis unless otherwise specified) is comprised of particles having a diameter less than said diameter value. As used herein, the term “D90” refers to a diameter at which 90% of the sample (on a volume basis unless otherwise specified) is comprised of particles having a diameter less than said diameter value. Particle size can be determined by light scattering techniques or analysis of optical digital micrographs. Unless otherwise specified, light scattering techniques are used for analyzing particle size.

As used herein, the term “crush strength,” with reference to gravel packing particles, refers to the stress load that the gravel packing particles can withstand prior to crushing (e.g., breaking or cracking). The crush strength values of the present disclosure are based on API RP-19C (Second Ed., September 2020).

As used herein, the term “gravel pack permeability” refers to a measure of a gravel packs ability to transmit fluids, measured in darcies (D) or millidarcies (mD). The gravel pack permeability values of the present disclosure are based on the API RP-19D entitled “Measuring the Long-term Conductivity of Proppants” (First Ed., May 2015).

As used herein, the term “gravel pack conductivity” refers to the product of gravel pack permeability over a defined width, measured in millidarcy-ft (mD-ft). The gravel pack conductivity values of the present disclosure are based on the API RP-19D entitled “Measuring the Long-term Conductivity of Proppants” (First Ed., May 2015).

All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” with respect to the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

As used in the present disclosure and claims, the singular forms “a,” “an,” and “the” include plural forms unless the context clearly dictates otherwise.

The term “and/or” as used in a phrase such as “A and/or B” herein is intended to include “A and B,” “A or B,” “A,” and “B.”

Petroleum Coke Gravel Packing Material, Methods and Systems

Sand control operations require effective gravel packing material forming a gravel pack to prevent production of unconsolidated formation particles while maintaining permeability and conductivity for production of wellbore fluid recovery, such as for hydrocarbon recovery. Effective gravel packing materials are typically associated with a variety of characteristics or properties, including efficient transport within a carrier fluid and sufficient mechanical strength to maintain permeability and conductivity of wellbore fluids once the wellbore is brought on production.

According to Stokes' law, the rate of settling of a particle of gravel packing material within a carrier fluid is directly proportional to the difference in density between the particle and the fluid. Thus, a gravel packing particle having a density that is closer to that of the carrier fluid is more likely to remain in suspension compared to a gravel packing particle having density that is much higher than that of the carrier fluid. Moreover, as will be appreciated, the petroleum coke gravel packing material of the present disclosure having lower apparent densities settle at a slower rate within an identical carrier fluid (thus having better transport) compared to higher apparent density particle sized gravel packing particles.

The apparent density of the petroleum coke gravel packing material of the present disclosure may be less than 1.7 grams per cubic centimeter (g/cc), including in the range of 1.3 g/cc to 1.7 g/cc, or 1.4 g/cc to 1.6 g/cc, or 1.3 g/cc to 1.6 g/cc, encompassing any value and subset therebetween. As provided above, traditional gravel packing particles generally have apparent densities greater than about 2.0 g/cc. Thus, the petroleum coke gravel packing particles described herein have substantially lesser apparent densities compared to traditional gravel packing particles, which is indicative of their comparably more effective transport and lower settling rates within a carrier fluid used as part of a sand control operation. Moreover, as described in greater detail below, the density of the carrier fluids for use in the embodiments of the present disclosure may be in the range of 1.0 g/cc to 1.5 g/cc, or 1.0 g/cc to 1.2 g/cc, encompassing any value and subset therebetween. Accordingly, the petroleum coke gravel packing particles also have a density closer to the desired carrier fluid compared to traditional gravel packing particles and will, as per Stokes' law, exhibit better suspension for this reason, as well.

The suspension and low settling rates of the low density petroleum coke gravel packing particles are further able to facilitate formation of comparatively longer gravel packs, such as for use in extended-reach wells, before a dune is formed in an alpha wave process. For the same reason, the low density petroleum coke gravel packing particles are able to prevent blockage of some or all perforation tunnels within a wellbore.

Further, as described hereinabove, the low density of the petroleum coke gravel packing particles permits a reduction in viscosifier (e.g., polymer) load in the carrier fluid, thereby reducing costs of the sand control operation and also permitting a reduction in pump rates compared to traditional sand control operations. As such, pump requirements can be comparably more flexible, fracturing of the formation can be better or completely avoided, and fines migration and shale spalling can be reduced or prevented during the sand control operations described herein. Moreover, selection of a petroleum coke gravel packing material having a similar density compared to the carrier fluid can further enhance pumping flexibility, such that if pumping must be stopped, the petroleum coke gravel packing particles will remain in suspension rather than settling to a heel of the wellbore.

In alternative embodiments, where the sand control operation is performed with a pre-packed screen, use of the low density petroleum coke gravel packing material would reduce the overall weight of the screen installation process, thus reducing torque and drag.

A gravel packing particle's crush strength is a measure of its ability to withstand compressive stresses within a formation (i.e., within the annulus between a screen and wellbore), as they must resist sustained loads during the lifetime of a wellbore to maintain gravel pack permeability and conductivity. Gravel packing particles that are not able to withstand the imposed stresses of produced fluid flow and/or formation movement will crush over time, resulting in the formation of fines that may be transported into the wellbore with produced fluids and accumulate in sufficient quantities to decrease production rates and/or necessitate costly wellbore remediation operations. Accordingly, gravel packing particles with higher crush strengths are favorable. According to API RP-19C standards, adequate gravel packing particles should have a crush strength in which minimum number of fines are produced under a stress of 2000 psi, depending on the size of the particular gravel packing particles.

The particular crush strength of gravel packing particles may depend on a number of factors including, but not limited to, the overpressure gradient, the depth of the wellbore, the integrity of the subterranean formation, and the like, and any combination thereof. The crush strength of gravel packing particles may further be at least partially dependent upon the size of the individual particles.

Traditional gravel packing particles have particle diameters in the range of about 50 micrometers (μm) to 2500 The petroleum coke gravel packing particles described herein are comparable in particle diameter size having a D50 of 50 μm to 500 or 100 μm to 400 or 150 μm to 350 encompassing any value and subset therebetween.

In some aspects, the crush strength of the petroleum coke gravel packing particles described herein may be in the range of 3000 pounds per square inch (psi) to 12,000 psi, or 3000 psi to 6000 psi, or 5000 psi to 10,000 psi, or 7500 psi to 12,000 psi, encompassing any value and subset therebetween.

Gravel pack efficacy is further related to permeability and conductivity, characterized by the fluid flow rate within a gravel pack under gradient pressure. Conductivity is the product of a gravel pack's permeability, k, and its thickness, h, and may be determined using Equations 1 and 2:

$\begin{matrix} {{C_{f} = {kh}},} & {{Equation}1} \end{matrix}$ $\begin{matrix} {{k = {\frac{1}{C}\frac{\phi^{3}}{\left( {1 - \phi} \right)^{2}}\sigma_{eff}^{2}\Phi_{s}^{2}}},} & {{Equation}2} \end{matrix}$

where C is a constant; ϕ is the gravel pack void fraction; a is the average particle size diameter of the gravel pack particles; and Φ is a shape factor related to the asphericity of the gravel pack particles. In tension with settling rate and transport, gravel pack conductivity favors gravel pack particles having larger average particle size diameters, narrow particle size distribution, and more spherical particle shapes across the distribution, as described below.

Accordingly the permeability and conductivity of a gravel pack is dependent at least in part on the shape of the gravel packing particles. In particular, gravel packing particles having a substantially consistent spherical shape may provide increased porosity through which produced fluids may flow while maintaining sand control. Moreover, gravel packing particles having a relatively narrow size distribution may additionally be preferred to maintain the integrity of the gravel pack, such that smaller (or irregular shaped) gravel packing particles do not fill voids within the gravel pack. The petroleum coke for use in forming the gravel packs of the present disclosure have substantially consistent size, as described above, and spherical shape without the need for grinding or milling; that is, after the refining process, the resultant petroleum coke (fluid coke and flexicoke) is readily available for gravel packing particle use. FIG. 1 illustrates a scanning electron microscope image (40× magnification) providing a representative embodiment of the shape of 40/70 mesh fluid coke petroleum gravel packing particles according to one or more aspects of the present disclosure. As shown, the sphericity and shape is substantially consistent.

The Krumbein Chart provides an analytical tool to standardize visual assessment of the sphericity and roundness of particles, including gravel packing particles. Each of sphericity and roundness is visually assessed on a scale of 0 to 1, with higher values of sphericity corresponding to a more spherical particle and higher values of roundness corresponding to less angular contours on a particle's surface. According to API RP-19C standards, the shape of a gravel packing particle is considered adequate for use in sand control operations if the Krumbein value for both sphericity and roundness is ≥0.6. The sphericity of the petroleum coke gravel packing particles of the present disclosure are in the range of 0.6 to 1, encompassing any value and subset therebetween. The roundness of the petroleum coke gravel packing particles of the present disclosure are in the range of 0.6 to 1, encompassing any value and subset therebetween.

The permeability and conductivity of a gravel pack comprising the petroleum coke gravel packing material of the present disclosure is comparable to traditional sand gravel particles, particularly at comparable particle sizes, as shown hereinbelow. Moreover, in some instances, depending on the selected petroleum coke gravel packing material, as defined and described herein, a greater permeability and conductivity compared to traditional sand gravel packing particles can be realized, as exhibited by their improved crush strength and thus decreased fines production under increasing stress.

In some aspects, the conductivity of the a gravel pack comprising the petroleum coke gravel packing material described herein may be in the range of 50 mD-ft to 1000 mD-ft, or 50 mD-ft to 800 mD-ft at a closure stress in the range of 1000 psi to 8000 psi, encompassing any value and subset therebetween.

In some aspects, the permeability of the gravel pack comprising the petroleum coke gravel packing material described herein may be in the range of 30 D to 100 D, or 30 D to 80 D at a closure stress in the range of 1000 psi to 8000 psi, encompassing any value and subset therebetween.

The petroleum coke gravel packing material having the characteristics described herein exhibit the aforementioned properties, as well as others, which make them not only a viable alternative for traditional gravel packing material, but further a surprising substitute with enhanced functionality. Moreover, the petroleum coke gravel packing material, although derived from refinery operations, exhibit only minimal metal leaching in a wellbore environment.

The petroleum coke gravel packing material described herein may be used as part of a gravel packing fluid for use in a sand control operation, the gravel packing fluid comprising a flowable (e.g., liquid or gelled) carrier fluid and one or more optional additives. This gravel packing fluid can be formulated at the well site in a mixing process that is conducted while it is being pumped in the sand control process. When the gravel packing fluid is formulated at the well site, petroleum coke gravel packing material can be added in a manner similar to the known methods for adding traditional gravel packing material (e.g., sand) into a gravel packing fluid. In various aspects, the fluid coke and/or flexicoke material received from a respective coking process are first processed (e.g., at the manufacturing facility, which may be at or near the well site) to remove any undesirably sized material that has adhered or otherwise conglomerated prior to use as the petroleum gravel packing particles described herein. Optionally, the removal process can be skipped, conducted at another facility, or performed in the field. In other or additional aspects, any fines may be preferably removed from the petroleum coke gravel packing material, such as by use of bag filters or sieves, whether in storage or during transport. As such, a more uniform or narrow size distribution may be obtained. In addition to the petroleum coke gravel packing material, it is within the scope of the present disclosure that such petroleum coke gravel packing material be included alone or in combination with one or more other traditional types of gravel packing particles. When petroleum coke gravel packing material is included in combination with another type of gravel packing material, the various particles can be mixed as a dry solid, mixed in a slurry, or added separately into a gravel packing fluid that is being formulated at the well site.

The carrier fluid of the present disclosure may be comprised of an aqueous-based fluid or a nonaqueous-based fluid. Aqueous-based fluids may include, but are not limited to, fresh water, saltwater (including seawater), treated water (e.g., treated production water), other forms of aqueous fluid, and any combination thereof. Nonaqueous-based fluids may include, for example, oil-based fluids (e.g., hydrocarbon, olefin, mineral oil), alcohol-based fluids (e.g., methanol), and any combination thereof.

One aqueous-based fluid class referred to as slickwater can be used with the low density petroleum coke gravel packing material of the present disclosure. Slickwater aqueous-based fluids have a relatively low viscosity of generally less than 20 centipoise (cP), or in the range of 1 cP to 20 cP, or 1 cP to 10 cP, or 1 cP to 5 cP, or 1 cP to 2 cP, encompassing any value and subset therebetween, and have low densities in the in the range of 1.0 g/cc to 1.5 g/cc, or 1.0 g/cc to 1.2 g/cc, encompassing any value and subset therebetween. As such, and unlike traditional high density gravel packing material, the petroleum coke gravel packing material suspended in a slickwater carrier fluid, whether additional additives are included or not, can be pumped at high flow rates, and thus at high turbulence, to facilitate maintaining the petroleum coke gravel packing particles in suspension.

In various aspects, the viscosity and density of the carrier fluid may be altered by foaming or gelling. Foaming may be achieved using, for example, air or other gases (e.g., CO₂, N₂), alone or in combination. Gelling may be achieved using, for example, guar gum (e.g., hydroxypropyl guar), cellulose, or other gelling agents, which may or may not be crosslinked using one or more crosslinkers, such as polyvalent metal ions or borate anions, among other suitable crosslinkers. It is to be noted, however, that because the petroleum coke gravel packing particles of the present disclosure exhibit particularly low density, the carrier fluid can be void of foaming or gelling agents or may otherwise comprise a reduced amount of foaming or gelling agents compared to a carrier fluid comprising traditional gravel packing particles.

In addition, the carrier fluids may comprise one or more additives such as, for example, dilute aids, biocides, breakers, corrosion inhibitors, crosslinkers, friction reducers (e.g., polyacrylamides), gels, salts (e.g., KCl), oxygen scavengers, pH control additives, scale inhibitors, surfactants, weighting agents, inert solids, fluid loss control agents, emulsifiers, emulsion thinners, emulsion thickeners, viscosifying agents, particles, lost circulation materials, foaming agents, gases, buffers, stabilizers, chelating agents, mutual solvents, oxidizers, reducers, clay stabilizing agents, and any combination thereof.

Generally, the petroleum coke gravel packing material loading within a carrier fluid is less than or equal to 15 pounds of petroleum coke gravel packing material per gallon (PPG) of the carrier base fluid (absent any additives or foaming/gelling agents), such as in the range of 0.5 PPG to 15 PPG, or 0.5 PPG to 10 PPG, or 2 PPG to 6 PPG, or 0.5 PPG to 2 PPG, or 0.5 PPG to 1 PPG, encompassing any value and subset therebetween.

The methods described herein include preparation of gravel packing fluid (comprising a carrier base fluid), which is not considered to be particularly limited, because the petroleum coke gravel packing material of the present disclosure are capable of transportation in dry form or as part of a wet slurry from a manufacturing site (e.g., a refinery or synthetic fuel plant). Dry and wet forms may be transported via truck or rail, and wet forms may further be transported via pipelines. The transported dry or wet form of the petroleum coke gravel packing material may be added to a carrier fluid, including optional additives, at a production site, either directly into a wellbore or by pre-mixing in a hopper or other mixing equipment.

The methods of sand control operations suitable for use in one or more aspects of the present disclosure comprising the use of petroleum gravel packing material involve high pump rates in relatively low viscosity carrier fluids (e.g., slickwater) into an annulus between a sand screen and a drilled wellbore. More particularly, the methods described herein include drilling a wellbore in a subterranean formation. The subterranean formation may be a conventional or unconventional substrate and the wellbore may be vertical, horizontal, or otherwise deviated or tortuous, hydrocarbon-producing (e.g., oil and/or gas) wellbores and water-producing wellbores. These wellbores may be in various subterranean formation types including, but not limited to, shale formations, oil sands, gas sands, and the like.

A sand control screen assembly is placed in the wellbore, the sand control screen assembly having a base pipe defining one or more flow ports for receipt of production fluids from the formation and a screen arranged about the base pipe. As such, an annulus is created between the screen and the wellbore (i.e., an inner wall of the wellbore). The gravel packing fluid comprising the petroleum gravel packing material of the present disclosure are pumped downhole and into the annulus to provide sand control. The sand control operations of the present disclosure may be performed in open hole completions or cased completions, without departing from the scope of the present disclosure.

Example Embodiments

Nonlimiting example embodiments of the present disclosure include:

Embodiment A: A gravel packing fluid comprising: a carrier fluid; and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having an apparent density of less than about 1.7 g/cc.

Embodiment B: A method comprising: introducing a gravel packing fluid into a subterranean formation, the gravel packing fluid comprising a carrier fluid and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having a density of less than about 1.7 g/cc.

Nonlimiting example Embodiments A or B may include one or more of the following elements:

Element 1: Wherein the gravel packing particles are composed of fluid coke.

Element 2: Wherein the gravel packing particles are composed flexicoke.

Element 3: Wherein the gravel packing particles have an apparent density in the range of about 1.3 g/cc to about 1.7 g/cc.

Element 4: Wherein the gravel packing particles have a crush strength of about 3000 psi to about 12000 psi.

Element 5: Wherein the gravel packing particles have an average particle size distribution in the range of about 50 μm to about 2500 μm.

Element 6: Further comprising second gravel packing particles composed of a material that is not fluid coke or flexicoke.

Embodiments A or B may be in any combination with one, more, or all of Elements 1 through 6, including 1 and 2, 1 and 3, 1 and 4, 1 and 5, 1 and 6, 2 and 3, 2 and 4, 2 and 5, 2 and 6, 3 and 4, 3 and 5, 3 and 6, 4 and 5, 4 and 6, 5 and 6, and any other nonlimiting combinations or 1 through 6.

Nonlimiting example Embodiment B may include one or more of the following elements:

Element 7: Further comprising: depositing the gravel packing particles in an annulus between a sand control screen assembly and the subterranean formation, thereby forming a gravel pack.

Element 8: Further comprising: depositing the gravel packing particles in an annulus between a sand control screen assembly and the subterranean formation, thereby forming a gravel pack, wherein the subterranean formation is an open hole wellbore.

Element 9: Further comprising: depositing the gravel packing particles in an annulus between a sand control screen assembly and the subterranean formation, thereby forming a gravel pack, wherein the subterranean formation is a cased hole wellbore.

Element 10: Wherein the gravel pack has a permeability in the range of about 30 D to about 100 D at a closure stress in the range of about 1000 psi to about 8000 psi.

Element 11: Wherein the gravel pack has a conductivity in the range of about 50 mD-ft to about 1000 mD-ft at a closure stress in the range of about 1000 psi to about 8000 psi.

Element 12: Further comprising: sequestering carbon in the subterranean formation in the form of the gravel packing particles.

Embodiment B may be in any combination with one, more, or all of Elements 7 and 8 through 12 or 7 and 9 through 12, including 7 and 8, 7 and 9, 7 and 10, 7 and 11, 7 and 12, 8 and 10, 8 and 11, 8 and 12, 9 and 10, 9 and 11, 9 and 12, 10 and 11, 10 and 12, 11 and 12, and any other nonlimiting combination of Elements 7 and 8 through 12 or 7 and 9 through 12.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about,” and take into account experimental error and variations that would be expected by a person having ordinary skill in the art. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the incarnations of the present inventions. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

One or more illustrative incarnations incorporating one or more invention elements are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating one or more elements of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in the art and having benefit of this disclosure.

While compositions and methods are described herein in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps.

To facilitate a better understanding of the aspects of the present disclosure, the following examples of preferred or representative aspects are given. In no way should the following examples be read to limit, or to define, the scope of the disclosure.

Examples

In the following examples, properties of petroleum coke gravel packing material of the present disclosure are compared to properties of traditional gravel packing material. Fluid coke gravel packing material was obtained from the Imperial Oil Refinery located in Sarnia, Ontario, Canada or the Syncrude Canada Refinery located in Calgary, Canada; flexicoke gravel packing material was obtained from the ExxonMobil Refinery located in Baytown, Tex. The control gravel packing particles used in the Examples are sand particles comprised of 100 mesh Texas brown sands mined for use as gravel packing particles in the Permian basin.

Size

The petroleum coke gravel packing material of the present disclosure was characterized by particle size using Laser Particle Size Analysis. The particle size distribution of fluid coke gravel packing particles is shown in FIG. 2A; and the particle size distribution of flexicoke gravel packing particles is shown in FIG. 2B.

As shown in FIG. 2A, about 85% of the fluid coke gravel packing particles by weight were within a particle size range of about 74 μm to about 425 μm. The average particle size (D50) of the fluid coke gravel packing particles was 168 μm; the D₁₀ value was 104 μm; and the D₉₀ value was 268 μm.

As shown in FIG. 2B, about 82% of the flexicoke gravel packing particles by weight were within a particle size range of about 74 μm to about 425 μm. The average particle size (D₅₀) of the flexicoke gravel packing particles was 197 μm, the D₁₀ value was 119 μm; and the D₉₀ value was 319 μm.

Sieving

Two (2) experimental samples (EX1 (source 1), EX2 (source 2)) of fluid coke gravel packing material and one (1) experimental sample (EX3) of flexicoke gravel packing material were sieved to obtain an average size of 100 mesh (149 μm). The various experimental samples were compared to control samples of the sand gravel packing particles (CL), each also having an average particle size of 100 mesh (149 μm).

These samples were tested as described hereinbelow; it is to be noted that not all experiments involve all of the experimental or control sample types.

Density

EX1 was tested in duplicate for density using API PR-19C for apparent density. The results are shown in Table 1 below.

TABLE 1 Sample Apparent Density (g/cc) EX1 (duplicate 1) 1.4-1.6 EX1 (duplicate 2) 1.4-1.6 CL 2.65

As shown in Table 1, the values for the apparent densities of the petroleum coke gravel packing particle samples exhibit substantially lower apparent densities compared to the CL sample.

Crush Strength

The samples were subject to increasing stress loads and the stress level, in pounds per square inch (psi), at which 10% of each sample was crushed to a size below the smallest initial sieve. The results are shown in Table 2 below.

TABLE 2 Sample Crush Strength (psi) EX1 11,000 EX2 9,000 EX3 9,000 CL (duplicate 1) 10,000 CL2 (duplicate 2) 8,000

As shown in Table 2, the fluid coke (EX1, EX2) and flexicoke (EX3) gravel packing material samples exhibited improved or comparable crush strengths compared to the CL samples. This result indicates that the lighter density petroleum coke gravel packing particles of the present disclosure can adequately form a gravel pack at crush strengths comparable to traditional sand gravel packing particles. Further, this illustrates that the petroleum coke gravel packing particles of the present disclosure resist the formation of fines that would reduce the permeability and conductivity of a gravel pack.

Permeability

Samples EX1, EX3, and CL were tested using API RP-19D for permeability, testing the rate and pressure drop of a 3% KCl solution flowing through formed gravel packs under increasing pressure. Loading was modified to 0.4 pounds per square foot (lb/ft²) at increasing closure stress. The results are shown in FIG. 3 . As shown, the fluid coke and flexicoke gravel packing material samples exhibit comparable permeability for a wide range of closure stresses to the control sample, further illustrating that the lighter density petroleum coke gravel packing particles of the present disclosure can adequately form a gravel pack compared to traditional sand gravel packing particles

Conductivity Samples EX1, EX3, and CL were tested using API PR-19D for conductivity, testing the rate and pressure drop of a 3% KCl solution flowing through formed gravel packs under increasing pressure. The conductivity is a measure of the permeability and the measured gravel pack bed thickness. In addition, a delayed coke, milled and sieved to 100 mesh (149 μm), was tested for conductivity for further comparison with the petroleum coke types of the present disclosure (fluid coke and flexicoke). The results are shown in FIG. 4A. The lower density fluid coke and flexicoke gravel packing samples show increased conductivity at the starting, lowest closure pressure. Over time, the fluid coke and flexicoke gravel packing samples show an initially higher rate of conductivity degradation with increasing closure stresses compared to the control sample, but above about 3000 psi of closure stress, the rate of conductivity degradation decreases, but remains comparable to the control. Notably, the delayed coke sample initially shows comparable conductivity to the experimental and control samples, but drops off immediately with increased closure stress, exhibiting no conductivity at 8000 psi. This result further indicates the difference between the fluid coke and flexicoke gravel packing particles of the present disclosure compared to other petroleum coke types.

Prior to, and after, the conductivity testing, the particle size distribution of the EX1, EX3 and CL samples were evaluated for comparison. The results are shown in FIG. 4B. Each of the EX1, EX3, and CL samples experienced a shift in particle sieve size distribution toward smaller mesh sizes after testing (applying closure pressure), but a larger fraction of the CL sample was finer in size (labeled “pan”) compared to the EX1 and EX3 samples at the end of testing. Without being bound by theory, it is believed that this result is associated with an increased ductility of the fluid coke and flexicoke gravel packing material compared to traditional sand. That is, gravel pack permeability loss may be more influenced by deformation and consolidation of gravel packing particles and because sand is more brittle compared to fluid coke and flexicoke, it will maintain its shape and permeability at certain stress levels, but begins to fail as stress levels increase.

Leaching

Sample EX1 was tested for metal leaching. 0.1 grams of EX1 gravel packing material was placed in 100 milliliters of deionized (DI) water and continuously stirred at room temperature for 24 hours. The results were tested for sulfur, strontium, and vanadium. EX1 had a concentration of about 8 parts per billion (ppb) of sulfur compared to about 4 ppb of a DI water control. Further EX1 exhibited minimal strontium of about 1 ppb and minimal vanadium of about 2.5 ppb.

Further leaching testing was carried out on sample EX1. In subsequent testing, 50 g of EX1 was placed in 50 milliliters of 3 different Texas regional produced water samples and continuously stirred at 180° F. (˜82° C.) for up to 7 days. The results were tested for sulfates, strontium, and vanadium. The sulfate concentrations in the three produced water samples after being stirred with EX1 did not vary more than 5% from the original sulfate concentration (this is within the accuracy of the ICP testing that was carried out). The produced water after being stirred with EX1 also exhibited minimal changes in strontium (˜10%) and minimal vanadium (<11 ppm); there was no vanadium in the produced water samples prior to mixing with EX1. Again, this illustrates the suitability of the petroleum coke gravel packing material of the present disclosure for use in sand control operations.

Accordingly, the fluid coke and flexicoke gravel packing material of the present disclosure are suitable for use in sand control operations.

Many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure and that when numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated.

Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples and configurations disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. 

What is claimed is:
 1. A gravel packing fluid comprising: a carrier fluid; and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having an apparent density of less than about 1.7 g/cc.
 2. The gravel packing fluid of claim 1, wherein the gravel packing particles are composed of fluid coke.
 3. The gravel packing fluid of claim 1, wherein the gravel packing particles are composed flexicoke.
 4. The gravel packing fluid of claim 1, wherein the gravel packing particles have an apparent density in the range of about 1.3 g/cc to about 1.7 g/cc.
 5. The gravel packing fluid of claim 1, wherein the gravel packing particles have a crush strength of about 3000 psi to about 12000 psi.
 6. The gravel packing fluid of claim 1, wherein the gravel packing particles have an average particle size distribution in the range of about 50 μm to about 2500 μm.
 7. The gravel packing fluid of claim 1, further comprising second gravel packing particles composed of a material that is not fluid coke or flexicoke.
 8. A method comprising: introducing a gravel packing fluid into a subterranean formation, the gravel packing fluid comprising a carrier fluid and gravel packing particles composed one or both of fluid coke and/or flexicoke, the gravel packing particles having a density of less than about 1.7 g/cc.
 9. The method of claim 8, further comprising: depositing the gravel packing particles in an annulus between a sand control screen assembly and the subterranean formation, thereby forming a gravel pack.
 10. The method of claim 9, wherein the subterranean formation is an open hole wellbore.
 11. The method of claim 9, wherein the subterranean formation is a cased hole wellbore.
 12. The method of claim 9, wherein the gravel pack has a permeability in the range of about 30 D to about 100 D at a closure stress in the range of about 1000 psi to about 8000 psi.
 13. The method of claim 9, wherein the gravel pack has a conductivity in the range of about 50 mD-ft to about 1000 mD-ft at a closure stress in the range of about 1000 psi to about 8000 psi.
 14. The method of claim 8, further comprising: sequestering carbon in the subterranean formation in the form of the gravel packing particles.
 15. The method of claim 8, wherein the gravel packing particles are composed of fluid coke.
 16. The method of claim 8, wherein the gravel packing particles are composed flexicoke.
 17. The method of claim 8, wherein the gravel packing particles have an apparent density in the range of about 1.3 g/cc to about 1.7 g/cc.
 18. The method of claim 8, wherein the gravel packing particles have a crush strength of about 3000 psi to about 12000 psi.
 19. The method of claim 8, wherein the gravel packing particles have an average particle size distribution in the range of about 50 μm to about 2500 μm.
 20. The method of claim 8, wherein the gravel packing fluid further comprises second gravel packing particles composed of a material that is not fluid coke or flexicoke. 